Field of the Invention
The present teaching relates to an inspection method for inspecting a substrate support portion configured to support substrates in exposure with an exposure device, an inspection apparatus, an exposure control method, and an exposure system. Further, the present teaching relates to a semiconductor device produced by utilizing such exposure system.
Description of the Related Art
In cases of producing semiconductor elements, liquid crystal elements and the like in a photolithography process, projection exposure devices are utilized to expose the pattern of a reticle (a photomask) to the semiconductor wafer on a stage (or a glass plate and the like) via a projection optical system. As an example of such projection exposure devices, exposure devices of step-and-scan type are known as carrying out exposure on one shot for a semiconductor wafer (to be referred to as a wafer hereinbelow) by relatively moving a reticle stage (i.e. a mask substrate with a mask pattern formed therein) to scan just one shot while irradiating with a slit-shaped light beam via a reticle pattern and a projection lens. In so doing, because the size of an exposure shot is determined by the relative distance of scanning between the long side of the slit (light) and the reticle stage, it is possible to enlarge the exposure shot.
In order for such kind of exposure device to hold the wafer motionlessly in a flat state, a wafer holder fixed on a wafer stage is to sucked the wafer and hold the same. When the exposure device continues the exposure, foreign substances come to adhere to the wafer holder such as resist residue and the like falling off the photoresist applied to the wafer. When the wafer is sucked and held on the wafer holder in this state, the foreign substances will deteriorate the flatness of wafer's exposure surface. This deterioration of flatness of the exposure surface becomes the cause of error of positional deviation and focus error in each shot region of the wafer, and turns out to be a major cause of deteriorating the yield rate in producing semiconductor elements. Therefore, exposure devices including a cleaning device are proposed for cleaning the wafer holder in such cases (for example, see Japanese Patent Application Laid-Open No. 2010-153407). According to this cleaning device, it is possible to clean the wafer supporting surface of the wafer holder by causing a cleaning member to contact with the wafer holder and moving the wafer holder via the wafer stage.